Some years after his conversion from Lutheranism to Orthodoxy, Fr. John says his reasons have crystallized. Here are the big four, but do read his whole blog post.
But the tipping point, Fr. John says, was something else. Check out his blog.In the final analysis, however, I would boil all the differences down to these main points:
- The Church is not a Platonic Republic (i.e., intrinsically or primarily invisible); i.e., an assembly of believers. Rather, it is and must be a visible entity, traceable through an unbroken link to the time of the Apostles. (The Lutheran Confessions, in my view, speak with two minds about this doctrine.)
- The end or purpose of salvation is not merely to be safe or make it to heaven, but to be in an undying union with God through Christ and the Spirit. That end or purpose is never fully achieved, just as a relationship is never exhausted. (This is a summary of theosis or, what "Lutheran Orthodoxy" called unio mystica.) This leads me to resonate with St Maximus the Confessor's speculation that sin and death did not necessitate the incarnation of the Son of God; rather, the original design, from eternity, was that the Son of God would become incarnate so that man could be in union with God.
- Tradition is not a custom nor merely a lens through which the church reads the Scriptures; rather, Tradition is the ongoing life of the Church (the Spirit in and of the Church) which, of course, cannot contradict Scripture but which also amplifies Scripture. (The Lutheran Confessions state that some of Tradition - e.g., liturgy - is indifferent; and insist, for those who take a quia subscription, that it is a lens.)
- Sin is certainly serious and is inherited; but it is not part of man's nature nor is it the primary problem. Rather, death is the primary problem, as seen by the fact that Christ purposefully took on passable flesh in order to suffer, die and rise. (The article on Free Will [FC SD II], when read understanding the philosophical underpinnings of the language, agrees that man is not by nature sinful.)